铂纳米空球的制备及其对甲醇氧化的电催化性能

以粒径为100nm的硒球作模板,在室温下批量合成了粒径约110nm、壳厚约5 nm的铂空球.采用扫描电子显微镜（SEM）、透射电子显微镜（TEM）、高分辨透射电子显微镜（HR-TEM）、选区电子衍射（SAED）、X射线衍射（XRD）、能量色散X射线谱（EDX）等检测技术表征了其形貌与结构;以甲醇为探针分子研究了铂纳米空球修饰玻碳电极对甲醇电氧化的催化性能.结果表明,由铂原子簇团构筑的多孔铂空球粒径均匀、分散性好、结构稳定、比表面积大、传质性能好,是甲醇氧化的理想催化材料.循环伏安（CV）结果表明:当甲醇氧化的电流密度0.10 mA·cm^-2,正扫时,铂纳米空球的氧化电位与实心铂纳米粒子及铂黑相比,分别负移了约110和64mV;负扫时,前者比后两者分别负移了约51与13 mV.经800圈循环伏安扫描后,正扫时,甲醇在铂纳米空球上氧化峰的电流密度为实心铂纳米粒子及铂黑上的13和15倍;负扫时,前者为后两者的19和38倍.表明铂纳米空球对甲醇氧化具有较好的催化活性和稳定性.     

以Ag为模板制备Pt纳米空球及其对甲醇氧化的电催化性能

以硝酸银为前驱体,聚乙烯吡咯烷酮(PVP)为表面活性剂,抗坏血酸(AA)为还原剂,在18℃下通过调节氢氧化钠的加入量合成了2种不同粒径的银溶胶;以银溶胶为模板,在室温下合成了不同粒径的铂包银(Ag@Pt)实心纳米粒子;用浓氨水除去Ag核得到球壳上含残留银的铂纳米空球[(Pt-Ag)hollow]及其修饰玻碳(GC)电极[(Pt-Ag)hollow/GC];再用电化学法除去(Pt-Ag)hollow/GC电极上的残留银后,制得铂纳米空球(Pthollow)修饰的GC电极(Pthollow/GC).采用扫描电子显微镜(SEM)、高分辨透射电子显微镜(HRTEM)、能量色散谱仪(EDS)和X射线衍射仪(XRD)等表征了Pthollow的形貌、组成和结构;以甲醇为探针分子,研究比较了Pthollow/GC和实心铂纳米粒子(Ptnano)修饰GC电极(Ptnano/GC)对甲醇氧化的电催化活性.结果表明,Pthollow分散性好,粒径比较均匀;球壳多孔,具有粗糙的内外表面,比表面积大,是由铂原子和多维多级的铂原子团簇构建的结晶度不高的多晶铂;Pthollow/GC对甲醇的电催化氧化活性明显优于Ptnano/GC电极,且大大降低了贵金属Pt的用量.     

Pt纳米空球壳厚的可控制备及对甲酸的电催化氧化

本文以约120nm的α-Se球为模板,抗坏血酸为还原剂,H2PtCl6为前驱体,通过改变氯铂酸的用量可控合成了不同壳厚的纳米铂空球（Pthollow）及其修饰玻碳（GC）电极（Pthollow／GC）;采用扫描电子显微镜（SEM）、高分辨透射电子显微镜（HR-TEM）、能量色散X射线（EDX）谱、X射线衍射（X-ray diffraction,XRD）谱和选区电子衍射（SAED）图等表征其形貌、组成与结构;以甲酸为探针分子,采用循环伏安和计时电流法研究了甲酸在Pthollow／GC电极上的电催化氧化行为．结果表明,所制备的Pthollow分散性好、粒径比较均匀,其多孔球壳是由多维多级的铂原子团簇所构建,呈现多晶铂的结构与性质;当RPt/Se=1．2时,所合成Pthollow。对甲酸的电催化氧化活性最高,且明显优于电沉积铂（Ptnano）修饰GC电极（Ptnano／GC）,为直接甲酸燃料电池（DFAFC）阳极材料的优化制备提供了一定的实验与理论依据,有潜在的应用推广价值．     

电化学制备二维“花状”Pt纳米结构及其对甲醇的电催化氧化

采用恒电流电化学技术在玻碳基底上制得二维"花状"Pt纳米结构(2D FPNs)样品,所用的电解液为HAuCl4+HClO4溶液,无需添加任何表面结构诱导的有机试剂,Pt纳米结构表面更"洁净",有较高的反应活性.扫描电子显微镜测试显示,2D FPNs样品是由球状纳米花构成,纳米叶子是构筑纳米花的最小单元.通过控制电沉积时间可调控球状Pt纳米花数的密度.高倍透射电子显微镜测试表明每个叶状纳米片沿着Pt(111)晶面定向生长.甲醇电催化氧化活性与电沉积时间有关.2D FPNs电极的甲醇的电催化活性稍高于商业Pt/C电极,却有更好的抗毒化能力,这可能归因于其特定的暴露晶面及表面的"洁净性".     

Pt/H-TiO2催化剂制备及其甲醇电催化氧化性能

以四氯化钛为前驱体,采用水热法合成二氧化钛纳米棒（TiO₂,白色）,在纯H₂气氛,将其550 ^oC热处理2 h,即得有氧缺陷和Ti³⁺填隙原子的二氧化钛纳米棒（H-TiO₂,灰黑色）. 将Pt纳米粒子（~ 1.9 nm）负载于此两种二氧化钛纳米棒上,制得Pt/TiO₂和Pt/H-TiO₂催化剂. XRD和XPS测试表明,氢处理TiO₂晶型没有变化,仍属金红石型,但增加了Ti-OH表面物种. 电化学测试表明,H-TiO₂载体能够增强氧在Pt表面的吸脱附能力,从而提高其甲醇电催化氧化活性,Pt/H-TiO₂电极甲醇氧化峰电流密度为Pt/TiO₂电极的1.6倍、Pt/C电极的2.1倍.     

微波合成Pt/WC催化剂及其对甲醇的电催化性能

分别采用微波加热乙二醇还原法(MW)和浸渍还原法(IR)制备以碳化钨(WC)为载体的Pt/WC催化剂, 并分别标记为: MW-Pt/WC及IR-Pt/WC. 用XRD、SEM对两种方法制备的复合材料的结构与形貌进行表征. 循环伏安测试结果表明MW-Pt/WC催化剂在酸性条件下的甲醇氧化性能比IR-Pt/WC催化剂更优, 表现在同一电位下MW-Pt/WC催化剂具有更高的电流且其氧化起始电位负移约30 mV, 还具有更大的电化学比表面积. 此外计时电流法实验结果表明MW-Pt/WC催化剂的稳定性高于IR-Pt/WC催化剂.     

Ni纳米催化剂的制备及其对葡萄糖电催化氧化的研究

采用等体积浸渍和程序升温还原的方法制备了不同Ni含量的Ni/AC纳米催化剂,并对其进行了形貌和结构表征。采用三电极体系和循环伏安法在碱性溶液中进行了其对葡萄糖催化氧化的电化学测试。结果表明,Ni/AC/GCE(修饰在玻碳电极上的Ni/AC)催化剂对葡萄糖有较强的电催化氧化作用。其中,20%的Ni/AC/GCE对葡萄糖电催化氧化作用最强,且随着葡萄糖浓度增加,响应电流显著增大,二者呈线性相关。20%Ni/AC/GCE催化剂对葡萄糖催化氧化的线性响应范围为0.2~6.5 mmol/L,相关系数为0.999,响应灵敏度是13.15μA/(mmol/L),最低检测限为35μmol/L。稳定性测试结果表明,20%Ni/AC/GCE有着良好的稳定性,每隔两天测试,运行三周后其响应电流仍能维持在95%以上。     

Pt纳米粒子修饰的多孔硅电极的制备及其电催化性能

通过循环伏安法电沉积使直径约为7 nm的Pt纳米粒子均匀地分散于多孔硅表面, 拟用作微型质子交换膜燃料电池的催化电极. 与刷涂法相比较, 电沉积Pt纳米粒子的多孔硅电极(Pt/Si)呈现出高的Pt利用率和增强的电催化活性. 当Pt载量为0.38 mg•cm−2时, 其电化学活性比表面积高达148 cm2•mg−1, 是刷涂相近质量的纳米Pt/C催化剂的多孔硅电极Pt-C/Si的2倍多；该修饰电极对甲醇氧化也呈现了增强的催化性能和好的稳定性, 在0.5 V(vs SCE)极化1 h后电流密度为4.52 mA•cm−2, 而刷涂了相近Pt量的Pt-C/Si电极的电流密度只有0.36 mA•cm−2.     

DMFC中甲醇渗透的电化学研究

设计并建立甲醇渗透测试体系和模拟直接甲醇燃料电池(DMFC)运行体系,分别考察静态条件下H-cell中甲醇的渗透和运行条件下甲醇渗透对OCV的影响.循环伏安和计时电流法测试表明:随着渗透时间的延长,阴极侧的甲醇浓度增加;甲醇浓度增加,氧化峰电流增大,峰电位正移,氢在电极表面的吸脱附受到抑制,同时甲醇的正向氧化电流曲线出现肩峰.模拟DMFC实验测试结果表明:OCV先逐渐上升,接着发生突降,大约1.5 h后趋于稳定.     

一步法制备纳米铂/石墨烯及电催化甲醇的交流阻抗和扩散系数测定

采用绿色还原剂抗坏血酸,一步法制备纳米铂/石墨烯。对其进行X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)形貌结构表征,铂纳米粒子均匀分散于纳米石墨烯片层褶皱间,有效减少了团聚现象。运用循环伏安法(CV)和计时电流法(CA)研究纳米铂/石墨烯对甲醇电催化氧化活性和稳定性,通过交流阻抗(EIS)定量测定,发现铂/石墨烯比铂具有更优异的电荷传输性能,电荷转移阻抗下降了34.8%。计时电量法(CC)测定得到甲醇在铂/石墨烯电极的表面扩散系数为1.42×10~(-9) cm~2·s~(-1)。与铂纳米粒子相比,纳米铂/石墨烯对甲醇电催化氧化具有更高的活性和稳定性,显著提高电极催化活性表面积和电荷传输及转移性能。     

Preparation of PdCo Bimetallic Hollow Nanospheres and its Electrocatalytic Activity for Oxidation of Formic Acid

The performance of the direct formic acid fuel cell (DFAFC) is considerably higher than the direct methanol fuel cell (DMFC) because of some characteristics of formic acid1. For example, formic acid is non-toxic. Formic acid has two orders of magnitude smaller crossover flux through a Nafion membrane than methanol2. In DFAFC, the concentration of formic acid can be as high as 20 mol/L, while the best concentration of methanol in DMFC is only about 2 mol/L3. Thus, the power density of …     

硫化锌纳米空心球：合成及光学性质研究

Cubic ZnS hollow nanospheres have been prepared by a simple and template-free solvothermal method. The reaction was accomplished between Zn powder and the in-situ prepared S8. The results of X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) show that the ZnS hollow spheres are composed of ultrafine nanoparticles. The average diameters of the hollow nanospheres are about 100 nm. Their photoluminescence (PL) spectra indicate that they have excellent optical properties.     

Synthesis of Hollow Platinum–Palladium Nanospheres with a Dendritic Shell as Efficient Electrocatalysts for Methanol Oxidation

Engineering the size, composition, and morphology of platinum‐based nanomaterials can provide a great opportunity to improve the utilization efficiency of electrocatalysts and reinforce their electrochemical performances. Herein, three‐dimensional platinum–palladium hollow nanospheres with a dendritic shell (PtPd‐HNSs) are successfully fabricated through a facile and economic route, during which SiO₂ microspheres act as the hard template for the globular cavity, whereas the triblock copolymer F127 contributes to the formation of the dendritic shell. In contrast with platinum hollow nanospheres (Pt‐HNSs) and commercial platinum on carbon (Pt/C) catalyst, the novel architecture shows a remarkable activity and durability toward the methanol oxidation reaction (MOR) owing to the coupled merits of bimetallic nanodendrites and a hollow interior. As a proof of concept, this strategy is also extended to trimetallic gold–palladium–platinum hollow nanospheres (AuPdPt‐HNSs), which paves the way towards the controlled synthesis of other bi‐ or multimetallic platinum‐based hollow electrocatalysts.     

Enhanced Oxygen Reduction and Methanol Oxidation Electrocatalysis over Bifunctional PtPdIr Mesoporous Hollow Nanospheres

Designing and constructing nano‐architectures with abundant reactive atoms exposed on the surface and widely open pore interiors is an effective strategy for highly efficient utilization of Pt‐based catalysts. Herein, we report a facile method to synthesize tri‐metallic PtPdIr mesoporous hollow nanospheres (PtPdIr MHNSs) by selective chemical removal of sacrificial metallic cores from pre‐constructed Pd@PtIr mesoporous nanospheres (Pd@PtIr MNSs). The unique nano‐architectures, with mesoporous shells interconnected into the interior hollow cavities and the synergistic electronic effect from tri‐metallic PtPdIr composition, enable the as‐synthesized PtPdIr MHNSs to be efficient bifunctional electrocatalysts for catalyzing both methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR).     

Pt/C催化剂对乙醇电氧化的粒径效应

利用有机溶胶方法, 通过控制溶剂挥发温度制备了具有不同粒径大小的Pt/C催化剂. 制得的Pt/C催化剂中, Pt粒子具有非常优异的均一性和良好的分散度. 电化学研究表明, 对于乙醇的电催化氧化, Pt/C催化剂存在着明显的粒径效应. 当Pt粒子粒径为3.2 nm时, Pt/C催化剂对乙醇的电催化氧化的质量比活性最佳. X射线光电子能谱(XPS)的研究显示, Pt/C催化剂对乙醇氧化的粒径效应与其零价Pt含量以及Pt粒子的比表面积密切相关.     

不同载量pt/c催化剂制备及其对甲醇氧化的电催化活性

有机溶胶法;pt/c催化剂; pt载量;甲醇     

Selective Functionalization of Hollow Nanospheres with Acid and Base Groups for Cascade Reactions

The inner‐surface functionalization of hollow silica spheres has rarely been reported and is still a challenging topic. Herein, we report a deacetalization–Henry cascade reaction catalyzed by dual‐functionalized mesoporous silica hollow nanospheres with basic amine groups (?NH₂) on the internal shell and carboxylic acid groups (?COOH) on the external shell. The selective functionalization has been realized by a combination of “step‐by‐step post‐grafting” and “cationic surfactant‐assisted selective etching” strategy. Compared to unisolated catalyst, the selectively isolated acidic and basic dual catalyst provides excellent catalytic performance for the deacetalization–Henry cascade reaction in terms of both activity (>99 %) and selectivity (95 %).     

Methanol Electrooxidation on Smooth Platinum Modified with Ru：the Influence of Ru Coverage and Potentials on Oxidative Current and Products

Methanol oxidation on smooth Pt electrode modified with differ-ent coverage of Ru was studied using cyclic voltammetry and potential step combined with differential electrochemical mass spectroscopy. The current efficiency of formed CO2 was calcu-lated from faraday current and ion current of m/z = 44. The results show that Ru modified Pt electrode with the coverage of ca. 0.3 has the highest catalytic activity for methanol electroox-idation, i. e. faraday current and the current efficiency of CO2 at the low potentials reach to the maximum. In addition, Ru loses its co-catalytic properties at the high potentials.